Heat exchangers such as, for example, corrugated plate-type exchangers, shell and tube-type exchangers, tube and fin-type exchangers, and other types of heat exchangers known in the art are used to transfer thermal energy between two fluids without direct contact between the two fluids. In particular, a primary fluid is typically directed through a fluid passageway of the heat exchanger, while a cooling or heating fluid may be brought into external contact with the passageway. In this manner, heat may be conducted through walls of the passageway to thereby transfer energy between the two fluids. In some applications, one or both of the fluids circulated through the heat exchanger could have a corrosive nature and, over time, erode the walls of the fluid passageway. Without intervention, the walls of the fluid passageway could eventually fail, causing contamination of and/or functional loss of the heat exchanger.
One method implemented by heat exchanger manufacturers to accommodate the corrosive nature of the fluid(s) circulated through heat exchangers is described in U.S. Pat. No. 4,263,966 (the '966 patent), issued to Östbo on Apr. 28, 1981. In particular, the '966 patent describes a heat exchanger having cores made of a material with a high heat conducting capacity. The cores are provided with a covering made of another material that does not chemically or physically interact with the medium flowing in contact therewith. The covering completely shields off the cores from direct contact with the medium, thereby minimizing the likelihood of corrosion.
Although the heat exchanger covering of the '966 patent may help to reduce the likelihood of the medium eroding the core material, it may be excessive for some applications and expensive. Specifically, in some applications, the medium may be corrosive during movement through only a portion of the core. In these situations, a complete shielding of the entire core may be unwarranted and inefficient. In addition, because extra manufacturing procedures are required to apply the covering to the entire core, the cost of implementing the covering may be substantial.
The disclosed heat exchanger is directed to overcoming one or more of the problems set forth above.